This application claims the priority of application 197 24 882.9, filed in Germany Jun. 12, 1997, the disclosure of which is expressly incorporated by reference herein.
The present invention relates to an adaptor for an open-end rotor spinning arrangement, which adaptor takes the form of an extension piece partly projecting into a cover element of a spinning rotor; the adaptor is exchangeable and adapted to the dimensions of the spinning rotor and is essentially rotationally symmetrical in shape. The adaptor comprises a centrical connecting channel which forms the first section of a yarn withdrawal channel. The adaptor also includes a traverse channel which forms the end section of a fiber feed channel, the entry opening of the traverse channel being located on a circumferential surface of the adapter and continuing a section of the fiber feed channel located in the cover element by means of a partition joint while the exit opening of the traverse channel projects into the spinning rotor. The adaptor also comprises a bearing surface located on the side of the adaptor facing away from the spinning rotor, which bearing surface is disposed, airtight, on a take-up surface of the cover element, against which the adaptor is disposable by means of at least one axially effective fixing device. The adaptor also comprises an eccentric centering element for fixing the adaptor to the take-up surface at an exact angle.
In the case of an adaptor of this type (European published patent 654 551), the bearing surface is conically formed and is drawn against the equally conically formed take-up surface by means of fixing elements. The bearing surface also comprises the partition joint, at which the part of the fiber feed channel located in the cover element is continued by the end section of the fiber feed channel located in the adaptor. It is extremely difficult, from the point of view of manufacturing, to make the conical surfaces, arranged to each other, to exactly the same degree of conicity. Even in the case of the smallest deviations in conicity or in the diameters, the end area of the fiber feed channel located in the adaptor and the section of the fiber feed channel located in the cover element are laterally out of line.
It is an object of the present invention to achieve an effective seal between the bearing surface of the adaptor and the take-up surface of the cover element using the simplest but nevertheless adequately exact production methods possible, without the end section of the fiber feed channel, located in the adaptor, being laterally out of line with the section of the fiber feed channel in the cover element.
This object has been achieved in accordance with the present invention in that the bearing surface takes the form of a plane ring surface, and in that the circumferential surface containing the partition joint is in the form of a cylindrical surface, and that only one fixing device is provided, and that the fixing device and the centering element are arranged--in relation to the yarn withdrawal channel--almost diametrically opposite each other.
Because the bearing surface takes the form of a plane ring surface, the manufacture of the bearing surface is on the one hand significantly easier than in prior art, and on the other hand more exact, in particular with regard to matching up with the arranged take-up surface. An airtight seal is obtained between the bearing surface and the take-up surface without any further intermediary sealing means being necessary. Because the circumferential surface takes the form of a cylindrical surface, a sufficiently exact production is also possible in this area, without the risk of there being a lateral misalignment inside the fiber feed channel at the partition joint. Because the centering element is arranged almost diametrically opposite to the fixing device a single fixing device is sufficient in practice, whereby an effective arrangement of the bearing surface of the adaptor on the take-up surface of the cover element is still obtained.
For the purpose of the present invention, the fixing device is provided in close proximity to the partition joint, so that the hold is particularly intensive at that point where sections of the fiber feed channel are disposed adjacently.
A location bore hole, arranged parallel to the yarn withdrawal channel, is advantageously arranged at the fixing device, which takes the form of a screw bolt, which location bore hole is provided with a thread-free entry opening. The location bore hole, parallel to the yarn withdrawal nozzle, ensures that between the adaptor and the take-up surface no misalignment takes place, because the thread-free entry opening for the screw bolt supports the bore hole in this action.
In certain preferred embodiments of the invention, the centering element comprises two centering ribs extending parallel to one another, which are arranged at a cylindrical guiding surface arranged at the cover element. Thus it is not so much a case of centering a setting plug into a bore hole, which would result in a relatively time-consuming assembly, but rather the guiding surface of a short pin needs only to be inserted between two ribs, whereby a considerable lateral clearance in longitudinal direction of the ribs is admissible. Only the distance between the ribs and the cylindrical guiding surface must be exactly right.